Docket Number: EPA-HQ-OPP-2009-0011 

www.regulations.gov 

Zinc, Zinc Salts and Zeolites 

Amended Final Work Plan 

Registration Review 

Case Number: 4099 

Approved By: 

Acting Director, Antimicrobials Division 

Date: 

/Z- tjfl'L 
Docket Number: EPA-HQ-OPP-2009-0011 

www.regulations.gov 

2 

Zinc, Zinc Salts and Zeolites AMENDED FINAL WORK PLAN 

Introduction

This document amends the Final Work Plan (FWP) for the registration review of Zinc, Zinc 

Salts and Zeolites. Since the publication of the September 2009 Final Work Plan, the Agency has 

reviewed the data requirements previously identified to support the registration review of Case 

4099 (Zinc, Zinc Salts and Zeolites). This document amends the September 2009 FWP to clarify 

the requirements and remove the following studies which will no longer be required to support 

the risk assessment: 

• 835.1110: Activated Sludge Sorption Isotherm 

• 835.1240: Leaching and adsorption/desorption 

• 835.2240: Photodegradation in water 

• 835.2410: Photodegradation in soil 

• 835.4100: Aerobic soil metabolism 

• 835.4400: Anaerobic aquatic metabolism 

• 870.31001

: 90-day Oral Toxicity-rodent 

• 870.31501: 90-day Oral Toxicity-non-rodent 

• 870.32501: 90-day Dermal- rodent 

• 870.37001

: Developmental Toxicity-rodent 

• 870.38001: Reproductive Toxicity- rodent 

Unless otherwise stated by the Agency, all other elements of the Agency's September 2009 Zinc, 

Zinc Salts and Zeolites FWP remain unchanged. 

Summary of Data Requirements

Summary tables of the data required to support the registration review of each of the five active 

ingredients in the Zinc, Zinc Salts and Zeolites Case (Zinc chloride (PC Code 087801), Zinc 

oxide (PC Code 088502), Zinc sulfate (PC Code 089001), Zinc (PC Code 129015), and Zinc 

sulfate monohydrate (PC Code 527200)) are presented below.

 

 

1

 These studies are no longer needed for risk assessment because information to assess potential risk to zeolite 

compounds will be submitted in response to the silver zeolite DCI anticipated to be issued as part of the Silver 

Compounds registration review (Case 4082 and Case 5015). 
Docket Number: EPA-HQ-OPP-2009-0011 

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Data Requirements for the Registration Review of Zinc Oxide (PC Code 088502) 

Guideline 

Number Anticipated Data Requirement Test Material 

Estimated Timeframe 

(Measured in months from DCI 

receipt) 

850.3300 or 

OECD 2092,3,4 Activated Sludge Respiration Inhibition TGAI 12 

835.12302 Sediment and soil adsorption/desorption TGAI 12 

850.41003,5,6,7 Seedling emergence, Tier II TGAI 12 

850.42505,6 Vegetative vigor dose response test using 

rice (Oryza sativa) 

TGAI 12 

850.44002,3,4,6 Aquatic plant growth using floating 

macrophyte Lemna gibba 

TGAI 12 

850.45002,3,6,8 Aquatic Plant Growth (green alga, 

freshwater diatom, saltwater diatom) 

TGAI 12 

850.45502,3,6,9 Aquatic Plant Growth (cyanobacteria) TGAI 12 

SS5,10 Aquatic Leaching from Wood TGAI 24 

SS5,11 Soil Leaching from Wood TGAI 24 

 

2

 Study is required to support the registration review of wood preservative uses, material preservative uses, and 

outdoor moss control uses. 

3

 Analytical measurements of zinc (total, dissolved, and free) and the following water quality parameters that are 

critical to metal speciation in solution are required: temperature, pH, dissolved organic carbon (distribution of humic 

and fulvic acids), major cation (Ca, Mg, Na and K), major anions (SO4 and Cl), alkalinity, and sulfide content. 4

 Because applied zinc and zinc salts will react in aqueous solutions to form free zinc ion and dissolved complexes, 

the Agency recognizes there is potential for tests conducted with one zinc active ingredient to potentially bridge to 

another. However, the Agency also recognizes that the content and formation of the free zinc ion and complexes in a 

test can be affected by dissolution and reaction kinetics and therefore data generated for one of the more soluble zinc 

active ingredient forms is recommended for use in such bridging. 

5

 Study is required to support the registration review of wood preservative uses. 

6

 Results from a tier II study are required to be submitted to satisfy this requirement. 7

 Seedling emergence was presented in the Final Work Plan as 850.4225; however, test guidelines 850.4100 and 

850.4225 were merged and harmonized into OCSPP 850.4100 in a Federal Register Notice dated June 27, 2012 

(FRL-9333-1). 

8

 Results for three species (Selenastrum capricornutum (green alga), one freshwater diatom, and one saltwater 

diatom) are required to fulfill requirement. If the NOAEC of the green alga is > 1 ppm zinc, the Agency may 

consider waiving data for other algal species. 

9

 Results for one species of cyanobacteria are required to fulfill requirement. If the NOAEC of the green alga is > 1 

ppm zinc, the Agency may consider waiving data for other algal species. 

10 For guidance, please refer to: Standard Method of Determining the Leachability of Wood Preservatives, American 

Wood Preservers’ Association (AWPA) Standard E11-06 or E11-12. 

11 For guidance, please refer to: Standard Method of Determining the Leachability of Wood Preservatives in Soil 

Contact, American Wood Preservers’ Association (AWPA) Standard E20-06 or E20-08. 
Docket Number: EPA-HQ-OPP-2009-0011 

www.regulations.gov 

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Data Requirements for the Registration Review of Zinc Chloride (PC Code 087801) 

Guideline 

Number Anticipated Data Requirement Test Material 

Estimated Timeframe 

(Measured in months from DCI 

receipt) 

850.3300 or 

OECD 2091,2,3 Activated Sludge Respiration Inhibition TGAI 12 

835.12301 Sediment and soil adsorption/desorption TGAI 12 

850.44001,2,3,4 Aquatic plant growth using floating 

macrophyte Lemna gibba 

TGAI 12 

850.45001,2,4,5 Aquatic Plant Growth (green alga, 

freshwater diatom, saltwater diatom) 

TGAI 12 

850.45501,2,4,6 Aquatic Plant Growth (cyanobacteria) TGAI 12 

 

1

 Study is required to support the registration review of wood preservative uses, material preservative uses, and 

outdoor moss control uses. 

2

 Analytical measurements of zinc (total, dissolved, and free) and the following water quality parameters that are 

critical to metal speciation in solution are required: temperature, pH, dissolved organic carbon (distribution of humic 

and fulvic acids), major cation (Ca, Mg, Na and K), major anions (SO4 and Cl), alkalinity, and sulfide content. 3

 Because applied zinc and zinc salts will react in aqueous solutions to form free zinc ion and dissolved complexes, 

the Agency recognizes there is potential for tests conducted with one zinc active ingredient to potentially bridge to 

another. However, the Agency also recognizes that the content and formation of the free zinc ion and complexes in a 

test can be affected by dissolution and reaction kinetics and therefore data generated for one of the more soluble zinc 

active ingredient forms is recommended for use in such bridging. 

4

 Results from a tier II study are required to be submitted to satisfy this requirement. 5

 Results for three species (Selenastrum capricornutum (green alga), one freshwater diatom, and one saltwater 

diatom) are required to fulfill requirement. If the NOAEC of the green alga is > 1 ppm zinc, the Agency may 

consider waiving data for other algal species. 

6

 Results for one species of cyanobacteria are required to fulfill requirement. If the NOAEC of the green alga is > 1 

ppm zinc, the Agency may consider waiving data for other algal species. 
Docket Number: EPA-HQ-OPP-2009-0011 

www.regulations.gov 

5 

Data Requirements for the Registration Review of Zinc Sulfate (PC Code 089001) 

Guideline 

Number Anticipated Data Requirement Test Material 

Estimated Timeframe 

(Measured in months from DCI 

receipt) 

850.3300 or 

OECD 2091,2,3 Activated Sludge Respiration Inhibition TGAI 12 

835.12301 Sediment and soil adsorption/desorption TGAI 12 

850.44001,2,3,4 Aquatic plant growth using floating 

macrophyte Lemna gibba 

TGAI 12 

850.45001,2,4,5 Aquatic Plant Growth (green alga, 

freshwater diatom, saltwater diatom) 

TGAI 12 

850.45501,2,4,6 Aquatic Plant Growth (cyanobacteria) TGAI 12 

 

1

 Study is required to support the registration review of wood preservative uses, material preservative uses, and 

outdoor moss control uses. 

2

 Analytical measurements of zinc (total, dissolved, and free) and the following water quality parameters that are 

critical to metal speciation in solution are required: temperature, pH, dissolved organic carbon (distribution of humic 

and fulvic acids), major cation (Ca, Mg, Na and K), major anions (SO4 and Cl), alkalinity, and sulfide content. 3

 Because applied zinc and zinc salts will react in aqueous solutions to form free zinc ion and dissolved complexes, 

the Agency recognizes there is potential for tests conducted with one zinc active ingredient to potentially bridge to 

another. However, the Agency also recognizes that the content and formation of the free zinc ion and complexes in a 

test can be affected by dissolution and reaction kinetics and therefore data generated for one of the more soluble zinc 

active ingredient forms is recommended for use in such bridging. 

4

 Results from a tier II study are required to be submitted to satisfy this requirement. 5

 Results for three species (Selenastrum capricornutum (green alga), one freshwater diatom, and one saltwater 

diatom) are required to fulfill requirement. If the NOAEC of the green alga is > 1 ppm zinc, the Agency may 

consider waiving data for other algal species. 

6

 Results for one species of cyanobacteria are required to fulfill requirement. If the NOAEC of the green alga is > 1 

ppm zinc, the Agency may consider waiving data for other algal species. 
Docket Number: EPA-HQ-OPP-2009-0011 

www.regulations.gov 

6 

Data Requirements for the Registration Review of Zinc (PC Code 129015) 

Guideline 

Number Anticipated Data Requirement Test Material 

Estimated Timeframe 

(Measured in months from DCI 

receipt) 

850.3300 or 

OECD 2091,2,3 Activated Sludge Respiration Inhibition TGAI 12 

835.12301 Sediment and soil adsorption/desorption TGAI 12 

850.44001,2,3,4 Aquatic plant growth using floating 

macrophyte Lemna gibba 

TGAI 12 

850.45001,2,4,5 Aquatic Plant Growth (green alga, 

freshwater diatom, saltwater diatom) 

TGAI 12 

850.45501,2,4,6 Aquatic Plant Growth (cyanobacteria) TGAI 12 

 

1

 Study is required to support the registration review of wood preservative uses, material preservative uses, and 

outdoor moss control uses. 

2

 Analytical measurements of zinc (total, dissolved, and free) and the following water quality parameters that are 

critical to metal speciation in solution are required: temperature, pH, dissolved organic carbon (distribution of humic 

and fulvic acids), major cation (Ca, Mg, Na and K), major anions (SO4 and Cl), alkalinity, and sulfide content. 3

 Because applied zinc and zinc salts will react in aqueous solutions to form free zinc ion and dissolved complexes, 

the Agency recognizes there is potential for tests conducted with one zinc active ingredient to potentially bridge to 

another. However, the Agency also recognizes that the content and formation of the free zinc ion and complexes in a 

test can be affected by dissolution and reaction kinetics and therefore data generated for one of the more soluble zinc 

active ingredient forms is recommended for use in such bridging. 

4

 Results from a tier II study are required to be submitted to satisfy this requirement. 5

 Results for three species (Selenastrum capricornutum (green alga), one freshwater diatom, and one saltwater 

diatom) are required to fulfill requirement. If the NOAEC of the green alga is > 1 ppm zinc, the Agency may 

consider waiving data for other algal species. 

6

 Results for one species of cyanobacteria are required to fulfill requirement. If the NOAEC of the green alga is > 1 

ppm zinc, the Agency may consider waiving data for other algal species. 
Docket Number: EPA-HQ-OPP-2009-0011 

www.regulations.gov 

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Data Requirements for the Registration Review of Zinc Sulfate Monohydrate (PC Code 

527200) 

Guideline 

Number Anticipated Data Requirement Test Material 

Estimated Timeframe 

(Measured in months from DCI 

receipt) 

850.3300 or 

OECD 2091,2,3 Activated Sludge Respiration Inhibition TGAI 12 

835.12301 Sediment and soil adsorption/desorption TGAI 12 

850.44001,2,3,4 Aquatic plant growth using floating 

macrophyte Lemna gibba 

TGAI 12 

850.45001,2,4,5 Aquatic Plant Growth (green alga, 

freshwater diatom, saltwater diatom) 

TGAI 12 

850.45501,2,4,6 Aquatic Plant Growth (cyanobacteria) TGAI 12 

 

1

 Study is required to support the registration review of wood preservative uses, material preservative uses, and 

outdoor moss control uses. 

2

 Analytical measurements of zinc (total, dissolved, and free) and the following water quality parameters that are 

critical to metal speciation in solution are required: temperature, pH, dissolved organic carbon (distribution of humic 

and fulvic acids), major cation (Ca, Mg, Na and K), major anions (SO4 and Cl), alkalinity, and sulfide content. 3

 Because applied zinc and zinc salts will react in aqueous solutions to form free zinc ion and dissolved complexes, 

the Agency recognizes there is potential for tests conducted with one zinc active ingredient to potentially bridge to 

another. However, the Agency also recognizes that the content and formation of the free zinc ion and complexes in a 

test can be affected by dissolution and reaction kinetics and therefore data generated for one of the more soluble zinc 

active ingredient forms is recommended for use in such bridging. 

4

 Results from a tier II study are required to be submitted to satisfy this requirement. 5

 Results for three species (Selenastrum capricornutum (green alga), one freshwater diatom, and one saltwater 

diatom) are required to fulfill requirement. If the NOAEC of the green alga is > 1 ppm zinc, the Agency may 

consider waiving data for other algal species. 

6

 Results for one species of cyanobacteria are required to fulfill requirement. If the NOAEC of the green alga is > 1 

ppm zinc, the Agency may consider waiving data for other algal species. 
Docket Number: EPA-HQ-OPP-2009-0011 Final Work Plan 

www.regulations.gov Registration Review 

United States Prevention, Pesticides September 2009 

Environmental Protection and Toxic Substances 

Agency (7510P) 

Zinc, Zinc Salts and Zeolites Final Work Plan 

Registration Review 

September 2009 

 

 

Docket Number: EPA-HQ-OPP-2009-0011 Final Work Plan 

www.regulations.gov Registration Review 

TABLE OF CONTENTS

Zinc, Zinc Salts and Zeolites Registration Review Team Members................... 1 

I. Introduction.................................................................................... 2 

II. Comments on Preliminary Work Plan ................................................ 2 

III. Risk Assessment and Data Needs ...................................................... 6 

IV. Timeline ..................................................................................... 14 

V. Glossary of Terms & Abbreviations .................................................... 15 

 
Docket Number: EPA-HQ-OPP-2009-0011 Final Work Plan 

www.regulations.gov Registration Review 

Zinc, Zinc Salts and Zeolites Registration Review Team

Human Health & Environmental Effects 

Nathan Mottl 

Srinivas Gowda 

Risk Management

Eliza Blair 

Lance Wormell 

Office of General Counsel

Philip Ross

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Docket Number: EPA-HQ-OPP-2009-0011 Final Work Plan 

www.regulations.gov Registration Review 

I. Introduction:

This is EPA’s Final Work Plan for the registration review of zinc, zinc salts and 

zeolites. The work plan includes the expected registration review timeline. The work 

plan also addresses public comments received concerning the Preliminary Work Plan in 

the Summary Document which was posted in the zinc, zinc salts and zeolites registration 

review docket, and any other comments concerning the initial docket postings. The 

Summary Document provided information on what EPA knows about the pesticide and 

what additional risk analyses and data or information the Agency believes are needed to 

make a registration review decision. 

The Agency has begun to implement the new Registration Review program

pursuant to FIFRA Section 3(g) and intends to review each registered pesticide 

approximately every 15 years to determine whether it continues to meet the FIFRA 

standard for registration. The public phase of registration review begins when the initial 

docket is opened for each case. The docket is the Agency’s opportunity to state clearly 

what it knows about the pesticide and what additional risk analyses and data or 

information it believes are needed to make a registration review decision. 

The Zinc, Zinc Salts and Zeolites Preliminary Work Plan was published in the 

federal docket on March 25, 2009. An amendment that included updated water-body 

impairment information was published in the federal docket on March 31, 2009. The 90-

day comment period ended on June 23rd, 2009. The Preliminary Work Plan document is 

available on www.regulations.gov, docket number EPA-HQ-OPP-2009-0011. 

II. Summary of Comments Received on Preliminary Work Plan:

EPA received one whitepaper containing several separate comments during the 

public comment period on the initial docket, described below. The data needs, work plan 

and timeline described in the Preliminary Work Plan remain as they were presented 

initially. This document makes final the work plan for the zinc, zinc salts and zeolites 

registration review process. 

Comment: The Agency has sufficient information to fully evaluate the potential risks 

of exposure to zinc or silver zeolites and should revise its registration review work plan 

accordingly.

Response: As cited on page 7 and 8 of “Summary of Human Health Effects Data 

for Zinc, Zinc Salts and Zeolites Registration Review Document”, dated March 4, 2009:

 The silver-zinc zeolites labels are unique from the rest of the zinc salt active 

ingredients because they are used for indirect food contact uses (countertops, appliances, 

kitchen hardware, tiles, food trays, food processing equipment, food storage containers, 

food packaging, food processing utensils). Because of the unique chemistry of the silverzinc zeolites and the fact that these products are used for indirect food uses, additional 

silver-zinc toxicity data are needed for a dietary assessment. 

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Docket Number: EPA-HQ-OPP-2009-0011 Final Work Plan 

www.regulations.gov Registration Review 

 According to EPA’s review1 “the registrant must submit or cite valid toxicology 

studies conducted with the end use formula silver-zinc product for sub-chronic toxicity in 

the rode, sub-chronic toxicity in the non-rodent, developmental toxicity in the rodent, and 

reproductive toxicity in the rodent. Separate toxicity studies with technical grade silver 

and technical grade zinc are not required, but toxicity data on the formula with the 

highest percentage of silver and zinc should be conducted. This will support other enduse formulations from the registrant containing lower percentages of silver and zinc.” 

 In reviewing silver and zinc containing compounds, AD decided that zeolites 

compounds may have their own toxicological pattern and zeolite-based silver-zinc active 

ingredients were not similar to salts of silver and hazards would need to be considered 

separately.2,3

 In summary, during registration of the silver-zinc zeolite products, the Agency 

had previously determined that the zeolites are unique chemically and toxicologically 

from the other silver and zinc products. The EPA concluded that chemically, zeolitebased silver active ingredients were not similar to salts of silver and zinc and hazards 

would need to be considered separately. 

 In registration review, EPA will examine the hazard databases for the silver-zinc 

zeolites and attempt to determine whether changes in science policy or deficiencies in the 

databases materially affected the overall risk picture. During the literature search the 

Agency identified the data gaps in the silver-zinc zeolite toxicology database based on 

the review of the existing Agency records. The data gaps are presented in Section III of 

this document. 

 The Agency could not conduct a dietary review because the proper toxicity 

information was not available as per an earlier Agency review. In addition to this 

review, other silver zeolite decision documents were referenced to provide context on the 

Agency’s position on toxicity data requirements as far as Silver and Silver-Zinc 

Zeolites.2,3

Comment: 90-day dermal toxicity in rodents - It is possible to conclude that 

zeolites are not expected to result in systemic toxicity from the dermal route of exposure. 

Based on their poor water solubility and ionic characteristics, these compounds are not 

expected to cross the intact skin barrier and dermal uptake is negligible. Even in the case 

of damaged skin, uptake is expected to be negligible because of poor water solubility and 

their ionic nature (Fruijtier-Polloth (2009) HERA (2004)).

Response: The Agency will review the sources [(Fruijtier-Polloth (2009) and 

HERA (2004)] during the registration review process to determine whether a waiver is in 

order. To date, the Agency is not aware of a 90-day dermal toxicity study that has been 

submitted or identified in the existing literature for silver-zinc zeolites and can not draw 

any conclusions on whether dermal absorption is negligible. 

Comment: 90-day oral, developmental, reproductive studies - Since the 

Agency failed to provide a clear explanation for its request for more data, publicly 

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Docket Number: EPA-HQ-OPP-2009-0011 Final Work Plan 

www.regulations.gov Registration Review 

available information on the reported effects from silver and/or silver/zinc zeolite-type 

products was reviewed to determine whether sufficiently different effects from those 

expected from either the active ingredient or the inert component could be identified. 

The registrant referenced publicly available EPA reviews of data submitted to 

EPA, and noted that it is extremely difficult to clearly identify from the EPA reviews 

exactly what comprised the test material, even in terms of the metal components of the 

zeolite. If other components were present in the test material, the potential effects 

associated with those components cannot be identified. The registrant concluded from 

these publicly-available reviews that no sufficiently different effects were found, and no 

further toxicity data should be needed to complete Registration Review. 

Response: The Agency has determined that there is a potential for dietary 

exposure in the registration review and provided context and references to support its 

position. The purpose of this registration review scoping document was to determine 

whether sufficient data are available to support registration review. Based on researching 

existing Agency reviews to date on the silver-zinc zeolites, this registration review 

concluded more toxicity data is needed for silver-zinc zeolites. This decision reflects 

previous Agency decisions and documents on file. The Agency has a limited toxicity 

database of existing literature and registrant submitted studies for silver-zinc zeolites and 

the Agency encourages submission of studies. The Agency has appreciated the feedback 

on the Preliminary Work Plan and the information provided by the registrant during the 

public comment period and anticipates further discussions at a later time. The EPA will 

review the public comment period submissions and will decide whether any of this data 

presented in the submission will affect the anticipated toxicity data needs.

 According to registration records, the Agency had required toxicity data for 

silver-zinc zeolites in the past. In fact, the existing silver-zinc zeolite existing labels 

(EPA Reg 40810-12, 40810-24, etc.) express toxicity data needs and stipulate only timelimited approvals to support the indirect food uses. The registrant pointed out some 

toxicity information on inert zeolite, silver, zinc, silver copper zeolites, and silver zeolites 

in their response submissions. However, the registrant did not cite many specific toxicity 

studies of silver zinc zeolites and the Agency can not draw any meaningful comparisons 

or conclusion based on limited information. The Agency needs specific silver-zinc 

zeolite toxicity data to make meaningful conclusions on the differing toxicity of silverzinc zeolites from other silver zeolites, and/or silver, and zinc ions, etc. to see if the 

toxicity is comparable or not. At this time the EPA has taken the position that toxicity of 

silver salts and silver zeolites are not comparable and in the review of Irgaguard B5000, 

the Agency were not able to resolve the existing toxicity data needs. 2,3 In the past for 

silver zeolites, the Agency has concluded that silver zeolite was not similar to salts of 

silver.2 There is uncertainty on how the addition of different proportions of silver and 

zinc ions in different zeolite carriers would influence the dose related toxicity in different 

target organs. 

Comment: Documentation has been submitted to FDA (as well as to EPA) that 

provides evidence that the IEC component of the Irgaguard products remain within the 

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Docket Number: EPA-HQ-OPP-2009-0011 Final Work Plan 

www.regulations.gov Registration Review 

preserved materials. These studies were conducted to support FDA Effective Food 

Contact Notifications (FCN#193, #248, #275, #294) for the Irgaguard products as 

components of polymers used in food packaging and other food contact surfaces as 

regulated by FDA under FFDCA Section 409. For each of the three Irgaguard products, 

Ciba conducted worst-case migration studies following FDA guidance to determine 

potential movement out of a preserved article into food that contacts the surface of the 

article. In accordance with FDA guidance, the Irgaguard product was incorporated into 

Low Density Polyethylene (LDPE), which is considered to be a worst-case scenario. The 

maximum use rate of the Irgaguard product was used (3% w/w of the polymer). Small 

plaques (1 x 4 inch) of the LDPE were then subjected to severe conditions to determine 

migration of components out of the LDPE into a food simulant. The severe conditions 

included large surface area to volume ratio, exposure to an extremely aggressive food 

simulating solvent (10% ethanol with 1% sodium chloride), exposure for up to 10 days at 

40o

C with a 2 hour preheat at 100oC. The 1% sodium chloride solution was added to the 

standard FDA solvent (10% ethanol) because use of the ethanol alone resulted in no 

detectable levels of any of the potential migrating compounds. Ciba conducted 

preliminary work with the standard FDA solvents (10% and 95% ethanol). There were no 

detectable levels of silver using either standard solvent. The addition of a 1% NaCl 

solution was found to increase the ionic strength of the extractants, resulting in low but 

detectable levels of silver. The sodium from the sodium chloride is preferentially 

exchanged with silver and zinc on the surface of the LDPE wafer and to ensure maximum 

solubility of the inorganic silver and zinc ions.

Response: The Agency currently has one silver-zinc migration study (MRID 

46174701): 

Viczkus, J. (2003) Migration Study From Low Density Polyethylene (LDPE) Into 10% 

Ethanol With 1% Sodium Chloride: Irgaguard B7000. Project Number: FDA2002N04, 

B7000. Unpublished study prepared by Ciba Speciality Chemicals Corp. 71 p. 

This study will be reviewed for acceptability during registration review. Thank 

you for bringing this information to our attention. If there are more silver-zinc migration 

studies, we would encourage submission of these documents as well. 

Comment: There is no evidence of developmental toxicity in studies conducted 

by Kanebo with a silver-zinc zeolite comparable to Irgaguard B5000 (MRID 41638502, 

42245403, 42653201, 42845701).

Response: The Agency will be reviewing the studies submitted by Kanebo 

(41638502, 42245403, 42653201, 42845701) for acceptability with GLN 870.3700 

during registration review. 

References 

1

Irgaguard B5000: Request for assessment of risk from proposed food contact uses of the 

active ingredient. Memorandum from T. McMahon, PhD to Dennis Edwards/Marshall 

Swindell/Tony Kish, U.S.EPA/AD. March 6, 2003. 

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Docket Number: EPA-HQ-OPP-2009-0011 Final Work Plan 

www.regulations.gov Registration Review 

2

U.S. EPA 2004a. Memorandum from J. Chen, PhD. to Norm Cook. Subject: Interim 

Position for Toxicological End-points for Silver. P.C. Code: 309200. 

3

U.S. EPA 2004b. Memorandum for T. McMahon to T. Kish/M.Swindell. Silver - 

Report of the Antimicrobials Division Toxicity Endpoint Committee (ADTC). October 

20, 2004. 

In addition to addressing the comments above, EPA has also included amended 

water body impairment information in this Final Work Plan. Please see “Revised Zinc, 

Zinc Salts and Zeolites Summary Document: Registration Review Preliminary Work Plan 

Addendum”, dated March 31, 2009, for additional information. 

In the Preliminary Work Plan, the Agency solicited comments on three specific 

topics: environmental justice, water body impairment, and trade irritants. No comments 

or information were received during the comment period concerning these issues. 

III. Risk Assessment and Data Needs:

A Reregistration Eligibility Decision (RED) was completed for elemental zinc in 

1992. However, to complete registration review, additional data are needed to conduct 

the human health and ecological risk assessments. 

Human Health Risk 

 Note: Several existing registrations exist for silver-zinc and zinc zeolites which 

are composed of zinc (elemental) (PC Code 129015). Zeolites are clay-like materials that 

can be combined with various metal ions. According to MRID 458033-01, “the silverzinc zeolites are silver-zinc ion-exchange products which are stabilized by an inert ion 

exchange carrier.” The silver-zinc zeolites labels are unique from the rest of the zinc salt 

active ingredients because they are used for indirect food contact uses (countertops, 

appliances, kitchen hardware, tiles, food trays, food processing equipment, food storage 

containers, food packaging, food processing utensils); drinking water contact uses 

(tubing, plumbing supplies and fixtures); dermal contact (apparel items and interior 

furnishings) and HVAC uses. The other zinc salts are not used for food contact products. 

There are currently no tolerances or exemptions for the requirement of a tolerance for any 

zinc salts in this registration review case. A tolerance or exemption from the requirement 

of tolerance may be needed for zinc portion of silver-zinc zeolites for these indirect food 

uses. 

Acute Toxicity

Zinc Chloride 

 Data from the existing RED indicates that zinc chloride has an acute toxicity 

category II for acute oral (rat). It is a corrosive for the skin and eyes (acute toxicity 

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Docket Number: EPA-HQ-OPP-2009-0011 Final Work Plan 

www.regulations.gov Registration Review 

category I). The acute inhalation study for zinc chloride is assigned as acute toxicity 

category III. 

Zinc Oxide 

 Data from the existing RED indicates that zinc oxide has an acute toxicity 

category IV for acute oral (rat). It is a not a skin irritant (acute toxicity category IV) and 

only a mild eye irritant (acute toxicity category III). The acute inhalation studies were 

waived for the technical active ingredient. 

Zinc Sulfate Monohydrate 

 Data from the existing RED indicates that zinc sulfate monohydrate has an 

acute toxicity category III for acute oral (rat). It is a mild eye irritant (acute toxicity 

category III). The acute inhalation, dermal and skin sensitization studies were waived for 

the technical active ingredient. 

Zinc (Elemental) 

 Data for zinc (elemental) was not available from the existing RED. However, 

data from a product toxicity review containing 1.36% zinc indicates that zinc (elemental) 

has an acute toxicity category IV for acute oral, acute dermal and acute inhalation. It is a 

mild skin irritant (acute toxicity category IV) and mild eye irritant (acute toxicity 

category III) and a nonsensitizer. 

Subchronic and Chronic Toxicity

 The Food and Drug Administration (FDA) considers zinc chloride as generally 

recognized as safe (GRAS) for use in foods and nutrients under 21 CFR 182.8985 and 21 

CFR 182.5991. The FDA also considers zinc oxide and zinc sulfate as GRAS for use in 

foods under 21 CFR 182.8991 and 182.8997, respectively. The FDA also considers zinc 

oxide and zinc sulfate as GRAS for use in nutrients under 21 CFR 182.5985 and 

182.5997, respectively. 

Zinc is ubiquitous in the environment and occurs in the earth’s crust at an average 

concentration of approximately 70 mg/kg. This ion exists in the form of zinc salts such 

as zinc sulfide, zinc carbonate, and zinc oxide. Zinc is also an essential nutrient in the 

body. For toxicological concerns, there are adequate toxicology studies in the zinc 

database to evaluate incidental oral exposures. At high levels, oral exposure to zinc in 

animal studies may result in toxic effects such as pancreatic and renal lesions as well as 

histological alterations in the pituitary and adrenal glands. In general, the levels of zinc 

causing these toxicological effects occur at much higher dose levels than the level 

recommended for nutritional use and that is naturally available in food. Zinc is widely 

distributed in plants and animals, and is normally present in food. Zinc is also a normal 

part of metabolism in all living organisms. Based on this information, no toxicological 

endpoints were selected. 

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However, the silver-zinc zeolites labels are unique from the rest of the zinc and 

zinc salts active ingredients because they are used for indirect food contact uses 

(countertops, appliances, kitchen hardware, tiles, food trays, food processing equipment, 

food storage containers, food packaging, food processing utensils). Because of the 

unique chemistry of the silver-zinc zeolites and the fact that these products are used for 

indirect food uses, additional silver-zinc toxicity data are needed for a dietary assessment. 

 According to the Agency’s review, “the registrant must submit or cite valid 

toxicology studies conducted with the end use formula silver-zinc product for subchronic 

toxicity in the rodent, subchronic toxicity in the non-rodent, developmental toxicity in the 

rodent, and reproductive toxicity in the rodent. Separate toxicity studies with technical 

grade silver and technical grade zinc are not required, but toxicity data on the formula 

with the highest percentage of silver and zinc should be conducted. This will support 

other end-use formulations from the registrant containing lower percentages of silver and 

zinc.” 

 In reviewing silver and zinc containing compounds, the Agency has suggested 

that zeolites compounds may have their own toxicological pattern. Zeolite-based silverzinc active ingredients are not similar to salts of silver and zinc, and hazards would need 

to be considered separately for each silver-zinc zeolite compound. 

Dietary and Drinking Water Exposure

 The Food and Drug Administration (FDA) considers zinc and zinc chloride as 

generally recognized as safe (GRAS) for use in foods and nutrients under 21 CFR 

182.8985 and 21 CFR 182.5991. The FDA also considers zinc oxide and zinc sulfate as 

GRAS for use in foods under 21 CFR 182.8991 and 182.8997, respectively. Due to low 

toxicity concerns, EPA will not conduct a dietary risk assessment for zinc and zinc salts. 

EPA believes that zinc and zinc salts are not a concern at the current registered levels 

which are similar to those occurring naturally in food. 

 It should be noted, however, that there are several end-use silver-zinc zeolite 

registrations that have dietary and drinking water uses. The Agency will be reviewing 

silver and other related compounds (e.g. silver-zinc zeolites) on a case-by-case basis to 

determine whether the compound is similar to an existing class (e.g., silver salts, silverzinc zeolites). For dietary exposure for silver-zinc compounds, the registrant must submit 

or cite valid toxicology studies conducted with the end-use silver-zinc product for 

subchronic toxicity in the rodent, subchronic toxicity in the non-rodent, developmental 

toxicity in the rodent, and reproductive toxicity in the rodent. Separate toxicity studies 

with technical grade silver and technical grade zinc are not required, but toxicity data on 

the formula with the highest percentage of silver and zinc should be conducted. This will 

support other end use formulations from the registrant containing lower percentages of 

silver and zinc. Once the Agency, receives the appropriate toxicity data, the Agency will 

need to conduct a dietary assessment for silver-zinc zeolite.

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Occupational and Residential Exposure

 

For zinc and zinc salts there are currently 15 registered labels. Most of the uses 

include handler exposure to mixing/loading soluble concentrates and wettable powders 

during manufacturing of material preservatives and wood pressure treatment exposures to 

zinc from ammonical copper zinc arsenate (ACZA). There would also likely be dermal 

and inhalation exposure applying zinc preservative sprays to moss on walkways and 

roofs. Occupational postapplication exposure scenarios would include dermal and 

incidental ingestion from contact with wood products (utility poles, building poles, 

foundation piling, marine piling, etc.) and residential postapplication exposures would 

include dermal and incidental ingestion to treated countertops and treated apparel and 

pressure treated decks. 

As mentioned in the toxicology section (section 2), zinc is ubiquitous in the 

environment and occurs in the earth’s crust at an average concentration of approximately 

70 mg/kg. Zinc is also an essential nutrient in the body and is GRAS in food as dietary 

supplements. At registered application rates, exposure to zinc salt pesticides is not likely 

to be higher than that which is found in ambient levels and at levels of zinc nutrient 

which are required by the human body. 

 For silver-zinc and zinc zeolites, the Agency may need to conduct occupational 

and/or residential exposure assessments, particularly from dermal contact, to treated 

apparel and incidental exposure via mouthing to treated fabrics. 

Aggregate and Cumulative Exposure

In examining aggregate exposure, EPA takes into account the available and 

reliable information concerning exposures to pesticide residues in food and drinking 

water, and non-occupational pesticide exposures. The Food and Drug Administration 

(FDA) considers zinc and salts as GRAS for use in foods. EPA believes zinc and salts 

are of low toxicity and EPA does not intend to develop aggregate exposure assessments 

for zinc and zinc salts to determine if certain use patterns pose any risk based on the 

calculated aggregate exposures. However, for silver-zinc zeolites, an aggregate 

assessment may be needed. At this time, EPA has not yet determined whether zinc and 

salts have a common mechanism with other compounds; consequently, a cumulative 

assessment will not be performed for either of these chemicals.

Anticipated Human Health Data Needs 

 In reviewing silver- and zinc-containing compounds, AD determined that zeolite 

compounds may have their own toxicological pattern and zeolite-based silver-zinc active 

ingredients were not similar to salts of silver and zinc and hazards would need to be 

considered separately for each silver-zinc zeolite compound. Therefore, for the purposes 

of registration review, toxicity data needs for the silver-zinc and zinc zeolites are as 

follows: 

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Human Health Toxicity Data Needs:

• (GLN 870.3100) 90-Day Oral Toxicity-rodent 

• (GLN 870.3150) 90-Day Oral Toxicity-non-rodent 

• (GLN 870.3250) 90-Day Dermal Toxicity-rodent 

• (GLN 870.3700) Developmental Toxicity- rodent 

• (GLN 870.3800) Reproductive Toxicity- rodent 

 Once the Agency receives and reviews these toxicological studies, additional 

occupational, dietary and aggregate assessments may be needed. Further information is 

available in “Summary of Human Health Effects Data for the Zinc, Zinc Salts and 

Zeolites Registration Review Decision Document” dated March 4, 2009. 

Anticipated Physical/ Chemical Property Data Needs 

All product chemistry data requirements have been fulfilled for zinc, zinc salts 

and zeolites. Therefore, no additional physical/chemical property data are needed. 

Further information is available in “Summary of Product Chemistry, Environmental Fate, 

and Ecotoxicity Data for the Zinc Salts Registration Review Summary Document”, dated 

March 31, 2009. 

Ecological Risk 

The metal zinc has been identified as a cause of impairment for water bodies 

listed as impaired under section 303(d) of the Clean Water Act, based on information 

provided at 

http://iaspub.epa.gov/tmdl_waters10/attains_nation_cy.cause_detail_303d?p_cause_grou

p_id=706 . This list indicates 437 impairments listed for zinc in water and 10 for zinc in 

sediment. The Agency will determine whether pesticide use was a contributor and/or 

determine if use might occur in these watersheds.

Environmental fate and ecological risk assessments have not been conducted for 

the active ingredients in this case. The Agency anticipates conducting environmental fate 

and ecological risk assessments for outdoor residential uses for control of moss on roofs, 

decks, steps, patios, walks, bricks, cement, sidewalks, fences, fence posts, foundations 

and other outdoor structures made of composition shingles, wood, gravel, brick and 

unpainted cement. 

Since most of the applied zinc salts will transform to zinc oxide/hydroxide, the 

ecological effects and environmental fate data requirements for zinc oxide are sufficient 

for the other active ingredients. For zinc chloride, the Agency anticipates needing some 

or all of, the ecological effects and environmental fate data requirements listed for zinc 

oxide in order to conduct the environmental fate and ecological risk assessments, 

including an endangered species assessment. 

The Agency has not conducted a risk assessment that supports a complete 

endangered species determination. The ecological risk assessment planned during 

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registration review will allow the Agency to determine whether zinc, zinc salts and 

zeolites’ use has “no effect” or “may affect” federally listed threatened or endangered 

species (listed species) or their designated critical habitats. When an assessment 

concludes that a pesticide’s use “may affect” a listed species or its designated critical 

habitat, the Agency will consult with the U.S. Fish and Wildlife Service and/or National 

Marine Fisheries Service (the Services), as appropriate. 

Anticipated Environmental Fate and Ecological Data Needs

The Agency anticipates needing the following data in order to conduct a complete 

environmental fate and ecotoxicity assessment, including an endangered species 

assessment for all uses: 

Environmental Fate Risk Assessment Data Needs: 

• (GLN 850.6800) modified activated sludge respiration inhibition; and 

• (GLN 835.1110) activated sludge sorption isotherm 

Ecological Risk Assessment Data Needs: 

• (GLNs 850.4400 & 850.5400) algal toxicity (Tier II) using freshwater green alga, 

Selenastrum capricornutum.

Potential Zinc Oxide Ecological Effects and Environmental Fate Data for Outdoor 

Wood Preservative Uses 

 If zinc oxide is intended for treatment of wood products used in outdoor scenarios 

(e.g., decks, decking materials, aquatic uses), the Agency anticipates needing some, or all 

of, the following data in order to conduct the environmental fate and ecological risk 

assessments, including an endangered species assessment. However, note that which data 

are required will depend on: the quantities of zinc oxide (and/or major degradates or 

metabolites) leaching from wood; the types of chemical(s) leaching from wood (e.g., 

parent compound, major degradates or metabolites); the outdoor use scenarios in which 

zinc oxide-treated wood may be used; and the Agency's evaluation of the leaching data 

along with the available use, effects, and exposure information for zinc oxide: 

Ecological Effects Studies: 

 To support registration of wood preservatives, the following ecological effects 

and environmental data are required. 

a. Required (R) Ecological Effects Data: 

Guideline Description of Data Requirement

Number

850.1010: Aquatic invertebrate acute EC50 using Daphnia magna (using TGAI and 

TEP) (satisfied); 

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850.1075: Fish acute LC50s with a coldwater (rainbow trout, preferred) and a 

warmwater (bluegill sunfish, preferred) species (using TGAI and Typical 

End-Use Product (TEP) (satisfied); 

850.2100: Avian acute oral LD50 with bobwhite quail (preferred) or mallard duck 

(using Technical Grade Active Ingredient (TGAI) (satisfied); 

850.4225: Seedling emergence - dose response using rice (Oryza sativa); 

850.4250: Vegetative vigor - dose response using rice (Oryza sativa); 

850.4400: Aquatic plant growth using floating macrophyte Lemna gibba; and 

850.5400: Aquatic plant growth (algal and aquatic plant toxicity) - Tier II (dose 

response) (using TGAI or TEP) – Four species: freshwater green alga, 

Selenastrum capricornutum, blue-green cyanobacterium, Anabaena flosaquae, the freshwater diatom, Navicula pelliculosa, and marine diatom,

Skeletonema costatum. 

b. Conditionally-Required (CR) Ecological Effects Data: 

850.1025: Oyster acute (shell deposition) or 

850.1055: Acute oyster embryo larval 

850.1035: Acute Mysid 

850.1045: Acute Penaeid 

850.1075: Acute Fish Toxicity (estuarine/marine species) Acute LC50s/EC50s using 

estuarine/marine organisms (fish) species (using TGAI and TEP); 

850.1300: Aquatic Invertebrate life cycle study (using most sensitive species - 

freshwater or estuarine/marine) Daphnid chronic toxicity test; 

850.1350: Aquatic Invertebrate life cycle study (using most sensitive species - 

freshwater or estuarine/marine) Mysid chronic toxicity test; 

850.1400: Fish early-life stage toxicity studies (using TGAI and most sensitive 

species - freshwater or estuarine/marine); 

850.1500: Fish (freshwater and/or estuarine/marine species) life cycle study (using 

TGAI); 

850.1710: Oyster BCF 

850.1730: Fish BCF 

850.1850: Aquatic organism bioavailability/biomagnifications, toxicity tests (using 

TGAI or PAIRA); 

850.1735: Whole sediment, acute invertebrates (freshwater) (using TGAI); 

850.1740: Whole sediment; acute invertebrates (estuarine/marine) (using TGAI); 

850.1950: Field testing for aquatic organisms (estuarine/marine) (using TEP); 

850.2200: Avian dietary LC50 with bobwhite quail and/or mallard duck (using TGAI) 

(satisfied); 

850.2300: Avian reproductive studies with bobwhite quail and/or mallard duck 

(using TGAI); and 

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None: Whole sediment - chronic invertebrates (freshwater and/or 

estuarine/marine) (using TGAI or TEP). 

850.3020: Honeybee acute contact LD50 (using TGAI); 

850.3030: Toxicity of residues to honeybees, “Honey Bee Toxicity of Residues on 

Foliage” (using TGAI); 

850.4300: Terrestrial Plants Field Study (using TGAI); 

850.4450: Aquatic Plants Field Study (using TGAI) 

c. Required Environmental Fate Data: 

Guideline Description of Data Requirement

Number

835.2240: Photodegradation in water (using TGAI or PAIRA); 

835.2240: Photodegradation in soil (using TGAI or PAIRA); 

835.1230/ Leaching and/ 

835.1240: Adsorption/Desorption studies (using TGAI or PAIRA); 

835.4100: Aerobic soil metabolism (using TGAI or PAIRA); 

None: Aquatic leaching from wood study. (For guidance refer to: Standard 

Method of Determining The Leachability of Wood Preservatives, 

American Wood-Preservers’ Association Standard E11-06); 

None: Soil leaching from wood study (AWPA E20-04) 

835.4400: Anaerobic aquatic metabolism (using TGAI or PAIRA); and 

850.6800: Modified activated sludge, respiration inhibition (using TGAI). 

d. Conditionally-Required (CR) Environmental Fate Data: 

835.4200: Anaerobic soil metabolism (using TGAI or PAIRA); 

835.4300: Aerobic aquatic metabolism (using TGAI or PAIRA); 

835.4400: Anaerobic aquatic metabolism (using TGAI or PAIRA); 

835.6200: Aquatic (sediment) [using Typical End-use Product (TEP)]; and 

None: Monitoring of representative U. S. waters (residue of concern). 

The above listed data requirements for zinc oxide will also satisfy data 

requirements for residential outdoor moss control uses of zinc chloride, zinc sulfate 

monohydrate, and zinc metal.

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IV. Timeline:

EPA has created the following estimated timeline for the completion of the zinc, 

zinc salts and zeolites registration review. 

Registration Review for Zinc, Zinc Salts and Zeolites 

Projected Registration Review Timeline

Activities Time 

Opening Docket 

Open Docket Completed March 2009 

Close Public Comment Period Completed June 2009 

Case Development 

Final Work Plan September 2009 

Issue DCI June 2010 

Data Submission June 2011 

Preliminary Risk Assessment June 2013 

Close Public Comment Period September 2013 

Registration Review Decision 

Proposed Registration Review Decision December 2013 

Public Comment Period March 2013 

Final Registration Review Decision & 

Begin Post-Decision Follow-up 2013 

Total (years) 4 

Next Steps:

A Data Call-In (DCI) will be developed regarding the data gaps listed under the 

“Risk Assessment and Data Needs” section. Also, human health and ecological 

assessments will be conducted for all uses. 

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V. GLOSSARY of TERMS & ABBREVIATIONS

ai Active Ingredient 

AR Anticipated Residue 

ASTM American Society for Testing and Materials 

AWPA American Wood Preserver’s Association 

CFR Code of Federal Regulations 

cPAD Chronic Population Adjusted Dose 

CSF Confidential Statement of Formula 

CSFII USDA Continuing Surveys for Food Intake by Individuals 

DCI Data Call-In 

DEEM Dietary Exposure Evaluation Model 

DFR Dislodgeable Foliar Residue 

DNT Developmental Neurotoxicity 

DWLOC Drinking Water Level of Comparison 

EC Emulsifiable Concentrate Formulation 

EDWC Estimated Drinking Water Concentration 

EEC Estimated Environmental Concentration 

EPA Environmental Protection Agency 

EUP End-Use Product 

FDA Food and Drug Administration 

FIFRA Federal Insecticide, Fungicide, and Rodenticide Act 

FFDCA Federal Food, Drug, and Cosmetic Act 

FQPA Food Quality Protection Act 

FOB Functional Observation Battery 

GENEEC Tier I Surface Water Computer Model 

IR Index Reservoir 

LC50 Median Lethal Concentration. A statistically derived concentration of a 

substance that can be expected to cause death in 50% of test animals. It is 

usually expressed as the weight of substance per weight or volume of water, air 

or feed, e.g., mg/l, mg/kg or ppm. 

LD50 Median Lethal Dose. A statistically derived single dose that can be expected to 

cause death in 50% of the test animals when administered by the route indicated 

(oral, dermal, inhalation). It is expressed as a weight of substance per unit 

weight of animal, e.g., mg/kg. 

LOC Level of Concern 

LOAEL Lowest Observed Adverse Effect Level 

μg/g Micrograms Per Gram 

μg/L Micrograms Per Liter 

mg/kg/day Milligram Per Kilogram Per Day 

mg/L Milligrams Per Liter 

MOE Margin of Exposure 

MRID Master Record Identification (number). EPA's system of recording and tracking 

submitted studies. 

MUP Manufacturing-Use Product 

NA Not Applicable 

NAWQA USGS National Ambient Water Quality Assessment 

NPDES National Pollutant Discharge Elimination System 

NR Not Required 

NOAEL No Observed Adverse Effect Level 

OPP EPA Office of Pesticide Programs 

OPPTS EPA Office of Prevention, Pesticides and Toxic Substances 

PAD Population Adjusted Dose 

PAIRA Pure Active Ingredient Radiolabelled 

PCA Percent Crop Area 

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PDP USDA Pesticide Data Program 

PHED Pesticide Handler's Exposure Data 

PHI Preharvest Interval 

ppb Parts Per Billion 

PPE Personal Protective Equipment 

ppm Parts Per Million 

PRZM/EXAMS Tier II Surface Water Computer Model 

Q1* The Carcinogenic Potential of a Compound, Quantified by the EPA's Cancer 

Risk Model 

RAC Raw Agriculture Commodity 

RED Reregistration Eligibility Decision 

REI Restricted Entry Interval 

RfD Reference Dose 

RQ Risk Quotient 

SCI-GROW Tier I Ground Water Computer Model 

SAP Science Advisory Panel 

SF Safety Factor 

SLN Special Local Need (Registrations Under Section 24©) of FIFRA) 

TGAI Technical Grade Active Ingredient 

TEP Typical End-Use Product 

USDA United States Department of Agriculture 

UF Uncertainty Factor 

WPS Worker Protection Standard